Fluid current conveyor system for sawdust-like material



Aug. 27, 1957 R. P. VASTINE FLUID CURRENT CONVEYOR SYSTEM FORSAWDUST-LIKE MATERIAL 4 Shee ts-Sheet 1 Filed Aug. 7, 1946 llllll El?[777 WYEF' HAY MST/NE Aug. 27, 1957 R. P. VAS I'INE 2,804,350

FLUID CURRENT CONVEYOR SYSTEM FOR SAWDUST-LIKE MATERIAL Filed Aug. 7,1946 4 Sheets-Sheet 2 RAY I? Merl/v5 Aug. 27, 1957 R. P. VASTINE2,804,350

FLUID CURRENT CONVEYOR SYSTEM FOR SAWDUST-LIKE MATERIAL.

Filed Aug. 7, 1946 4 Sheets-Sheet s BQY MST/IVE Aug. 27, 1957 R. P.VASTlNE FLUID CURRENT CONVEYOR SYSTEM FOR SAWDUST-LIKE MATERIAL FiledAug. 7, 1946 4 Sheets-Sheet 4 RAY I? k srr/ve United States Patent '0FLUID CURRENT CONVEYOR SYSTEM FOR SAWDUST-LIKE MATERIAL Ray P. Vastine,Oak Park, 111., assignor, by mesne assignments, to Vastine Engineering;Company, Inc., Forest Park, 111., a corporation of'lllinois The presentinvention relates to a sawdust. burning system and involves a method of,as well asfor,,bur-ning sawdust as a fuel in a furnace, efficientlyandwithout smoke.

The present invention has for an object the provision of a method ofefliciently burning sawdustas a fuel in a furnace.

Another object of the invention is to provide a system for burningsawdust and the like as a fuel in a furnace which system operatesautomatically in accordance with steam pressure conditions in theboiler. f

Another object of the present invention isto provide means forefficiently burning sawdust in a furnace with out the creation of smoke.

A further object of the present'invention is to provide a sawdustburning system in whichthe sawdust is' charged into a furnace in aspread condition so that all of the sawdust will be ignited and burnefliciently and smokelessly.

Another object of the present invention is to provide a sawdust fuelburning system in which the ,sawdust is Withdrawn from a source ofsupply by suction and delivered-under pressure into a furnace;

A still further object of the present invention is to provide a sawdustfuel burning system in which the rate of delivery of the sawdust to aboiler'furnace is regulated in accordance with the steam pressureconditions in the boiler.

Another and further object of the present invention is to provide asawdust burning method in which sawdust iswithdrawn from a supply andagitated. The agitated sawdust is removed by suction and delivered in asuspended condition in an air stream under positive pressure into afurnace.

The invention has for a further object-the provision of a nozzle forspreading the sawdust as it is discharged into the furnace.

Another and yet further object of the present invention is toprovide asystem as just described in which auto matically functioning controlsare provided for operating thesystem in accordance withpressure"conditions in the boiler;

Generally speaking, the invention involves the provision of a supply ofsawdust, means for. withdrawing portions of the sawdust of the supplyanddelivering it to a pickup compartment wherein air under negative pressure picks up the sawdust and withdraws it in suspension by means of asuction stream. The suction stream with the suspended sawdust in it isconverted to a positive pressure stream and delivered with the sawdustinto a furnace. A single instrumentality is employed for cre ating thesuction and the positive pressure. Because of thei fact that a highpositive pressure is necessary to create suction sufficient to Withdrawthe sawdust from the compartment; means are provided for venting theductwhich carries the sawdust in the positiveair pressure stream-so thatthe air pressure and velocity in the duct Willbe reduced to avaluesuflicient-to carrythe sawdust ice in suspension into the furnace. Alsoa nozzle is employed which spreads the dust as it enters the furnace tothereby prevent the sawdust from piling upon the floor of the furnace,which spread delivery enables ready combustion of the sawdust withoutcreating smoke, as the dust is burned before reaching the floor of thefurnace.

The above, other and further objects of the present invention willbeapparent from the following descrip tion and accompanying drawings.

An embodiment of the present invention is illustrated in theaccompanying drawings and the views thereof are as follows: 7

Figure 1 is a side elevational view, somewhat schematically illustrated,of the system of the present invention as arranged for supplying sawdustto the furnace of a boiler;

Figure 2' is a top plan view of the arrangement of Figure 1 showing themanner of supplying sawdust to the furnaces of twoboilers;

Figure 3 is a fragmental side elevational View of th pickup-compartment,with a part in section, showing in dottedlines a. screw conveyor. formoving sawdust from a bin to thecompartment;

Figure 4 is a vertical sectional view taken in the plane of lineIV-IV'of Figure 3 V Figure 5 is a. horizontal sectional view, takeninthe plane V'V of Figure 3, with some parts in elevation;

Figure 6 is an end view of the pick-up compartment, in section, withsome parts in elevation, taken in the plane of line VIVI of Figure 3;and

Figure 7 is a schematic wiring diagram for the reversing motor showingconnections of the reversing motor to certain of the operating elementsof the'system. v

The drawings will now be explained.

A bin 15 is provided for containing a supply of sawdust. Extending fromor formed as a part of the bin is a duct 16 terminating in a pick-upcompartment 17.

Means are provided for moving sawdust from the bin 15 to the pick-upcompartment 17. The means herein illustrated comprises a spiral or screwconveyor 18 mounted on a horizontal axis having its rear end somewherewithin the bin 15 and its front end 18a in the pickup compartment 17. Ashaft 19 supports the conveyor and projects through the front'wall 20 ofthe pick-up compartment to which projecting end ofthe shaft drivingmeans are connected, aswill be later described.

Referring to Figure 4 it will be observed that the duct 16 is preferablyrectangular in cross section. The duct, including the pick-upcompartment 17, is closed on four sides for a distance from the frontwall. 20 through the bin wall 21 and for a short distance into the bin(thereby defining a closed intermediate portion of the casing).Rearwardly of the covered inward portion of the duct the top is open (soas to define a material receiving opening) and inclined side wings 22and'22a are formed'along the conveyor for receiving sawdust from the'bin. to direct it to the conveyor 18'. The duct 16 and pickupcompartment 17 thus comprise a casing or housing having a materialreceiving opening adjacent one end, a closed intermediate portion, and arestricted material discharge opening at the other end, which dischargeopening 15 will be described in detail hereinafter.

In order to compact the sawdust about the conveyor 18 to prevent thesawdust from falling away along the upper portion of the conveyor a-tubesurrounds'the conveyor 18 from its front end 18a to a point-146'adjacent the rear end of the cover of the duct 1 6 (Figure 3) from thatpoint, rearwardly the tube becomes a semicylindrical trough 147,terminating adjacent the inner end of the conveyor. The interiorof thetube 145 'is radially spaced from the periphery of the conveyor 13 buta-slightdistance which is suflicient to allow pieces of wood, which maybe in the trough to the pick-up compartment 17.

By compacting the sawdust in the tube 145, as long as thereis amplesawdust in thebin, the sawdust in 'the tube fills it completely, therebypreventingany from falling away along the top of the tube, which fallingaway would result in air channels through the sawdust in the tube whichwould disrupt the effectiveness of the suction air stream in withdrawingsawdust from the pick-up compartment, as the suction air stream passesunderneath the bottom of the pick-up compartment.

7 An air duct 23 is erected behind the bin wall 21 and near it, invertical position, and has its open upper end 24 communicating with theinterior of the bin above the supply of sawdust in the bin. A damper 148is arranged within the duct 23 to control flow of air throughthe duct.The damper is set at the time of installation of the duct.

Referring to Figure 4, it will be noted that the bottom of the conveyortrough 25 is arcuate, which bottom extends from the inner end of theconveyor to the point 26 (Figure 3) adjacent the pick-upcompartment. Aswill be noted in Figure 3, the point 26 is slightly ahead of the frontend 18a of the conveyor. From the point 26 to the front wall 20 of thepick-up compartment the bottom of the compartment is open, as at 155, asmay be observed in Figures 3 and 6.

The lower end of the air duct 23 communicates with a hood 27 which inturn communicates with duct means 28 for delivering air from the duct 23to the pick-up compartment 17, from what is shown in Figure 6 as theright side.

Leading from the lower part of the pick-up compartment 17, and from theleft side thereof as viewed in Figure 6, is a duct 29.

Mounted on a platform 30 supported by posts 31, above the boiler roomfloor F, isa blower B. The duct sawdust, to pass along the 29communicates with the inlet of the blower. A duct 3 32 communicates withthe outlet of the blower and leads to the furnaces or furnace to besupplied with sawdust as a fuel.

Referring to Figure 2 boilers X and Y are disposed in side by siderelation to be fired by sawdust as a fuel. The outlet duct- 32communicates with a junction box 34 from which a branch duct 35 leads tothe furnace 36 of the boiler X. Another branch duct 37 leads to thefurnace of the boiler Y. The junction box 34 has means within it forproportioning the amount of fuel delivered to the furnaces of boilers Xand Y, shouldthere be need for differential supply to the furnaces.

Each of the branch ducts 35 and 37 discharges into its furnace through adivergent nozzle 38. As maybe noted in Figure 1 the nozzle38 is directedin downwardly inclined position and is arranged to discharge into thefurnace 36 through the front wall 39 of the furnace, above In theconnection between the shaft 19 and the speed reducer 44 is a shear pinwhich breaks when some foreign object enters the conveyor and tends toretard the movement of the conveyor. I

As shown, the shift rod 45' of. the drive 43 is pivoted at 46 to aswinging lever 47. The lever 47 is pivoted by i one end at 48 to a lug49 integral with the casing of V the Reeves drive.

i For swinging the lever 47. to actuate the Reeves drive in a manner tochange speeds,,a reversing mot0r50 is employed.

As shown diagrammatically in Figure 7, the reversing motor 50 has acrank 51connected at one end to the motor shaft 52 and at the other endto one end of a link 53. The other end of the link 53 is pivoted at 54to the lever 47.

The reversing motor 50 is electrically controlled by means responsive tothe steam pressure conditions in the boiler. 7

Figure 7 shows a' circuit including a lead-in wire 55 in which is aresistance winding 56 from which a connection is made to the motor 50 bya conductor 57. A swinging contact finger 59 is pivoted at 60, fromwhich pivot electrical connection is made to the motor 50 by a conductor61. The other lead wire is designated as 58.

For swinging the contact finger 59 steam pressure responsive means areprovided. The means herein shown include a pipe 62 communicating withthe steam space of the boiler, which pipe enters a Sylphon bellows 63,one end of which 65 is fixed, the other end of which carrying a nose 64,is movable. The nose 64 is suitably connected to the contact finger 59,to move it as the bellows expands and contracts in accordance with steampressure conditions in the boiler.

7 By means of the arrangement just described the Reeves drive 43 isactuated by the reversing motor 50 in accordance with the rise and fallof steam pressure conditions in the boiler.

Inasmuch as the Reeves drive is operatively connected to the conveyor 18for rotating it to feed sawdust from the bin 15 to the pickupcompartment 17, the rate of feed of the sawdust by the conveyor is thusmade responsive to steam pressure conditions in the boiler. As the steampressure falls the speed of the conveyor is increased, and as thepressure rises the speed of the conveyor is reduced.

Other means responsive to pressure conditions in the boiler are utilizedfor starting and stopping the conveyor drive motor 42.

Inasmuch as it is necessary to operate the blower. B to createsuificient suction in the duct 29'to withdraw sawdust from the pick-upcompartment 17 and deliver it to the blower, more pressure is created inthe blower than is necessary to discharge the sawdust into a furnace.

In order to reduce the positive pressure and velocity between the blowerand the furnace to a value which is sufficient to carry the sawdust intothe furnace and discharge it thereinto under proper conditions andpressure, means are provided for venting the duct 32 between theblowertand the furnace.

The illustrated form of such venting means includes a pipe 67 having aplurality of branch connections, three of which are shown as '68, 69 and70, to the duct 32 and opening into the dust bin. A pipe 71 leads fromthe pipe 67 and is connected into the duct means 28 adjacent the pick-upcompartment 17 as shown in Figure 6. Thus air under positive pressure,in excess of that necessary to discharge the sawdust into the furnace,is withdrawn from the duct 32 and delivered into the pick up compartment17 or, if desired, into the bin. The branch connection 68, 69 and areprovided with dampers or valves 72 (Figure 7) which valves are connectedby a -link 73 to the lever 47 and the link 53 of the Reeves drive. Thus,the dampers or valves 72 are connected to be operated by the reversingmotor 50 to thereby regulate the valves 72 in accordance with steampressure conditions inthe boiler. V

The operationof the reversing motor 50 is such that the maximum amountof air under positive pressure is reversing motor will function toreduce the speed of the conveyor drive and to operate the valves 72 in amanner to reduce the pressure and velocity of the air entering thefurnace.

The bottom of the duct 16 between the point 26 and the end plate 20 ofthe pick-up compartment 17 is provided with an opening 155, shown inFigures 5 and 6 as rectangular. The length of the opening issubstantially the diameter of the flight of the conveyor. The width ofthe opening is such that the area of the opening is equal to one-half,or slightly less, of the cross-sectional area of the passageway 156 inthe lower portion of the pick-up compartment 17. a

While the present system has been devised, primarily, for utilizingsawdust as a fuel, it has been found satisfactory for utilizing dustmade from Masonite, or like wood products, and could be used in burningfeathers as a fuel it a sufficient supply were at hand; Accordingly theword sawdust is herein used generically and not by way of limitation.

The operation of the system is as follows:

At the commencement of firing, the boiler pressure is low, hence thereversing motor 50 is energized to actuate the Reeves drive 43 at highspeed which, in turn, operates the conveyor 18 at high speed to supplysawdust for fuel. The blower B operates at constant speed. As soon asthe blower B begins to run, a suction is created down through the pipe23 through the pick-up compartment 17 and up through the duct 29 to theinlet of the blower. The suction stream from the duct or pipe 23 entersthe passageway 156 and passes upwardly through the duct 29 thus carryingwith it sawdust which has accumulated in the bottom of the passagewayand in front of the conveyor, thus picking up the sawdust in suspensionand carrying it through the blower where the suction stream is changedto a pressure stream and delivered into the furnace. The Reeves drive,being operable by the reversing motor 50, actuates the dampers 72 tovent the duct 32, between the blower and the furnace, to reduce thepressure and velocity of the air stream in this duct to a point where itis sufficient to carry the sawdust into the furnace but not too high asto efiect proper combustion in the furnace. The air that is thus ventedpasses downwardly through the duct 71 and into the passageway 156 at thelower end of the pick-up chamber.

By reason of the fact that the sawdust is packed firmly about theconveyor within the tube 145, it accumulates sawdust ahead of the end18a of the conveyor on the bottom of the passageway 156. Packingtof thesawdust in the tube 145 prevents creation of air channels through thetube. If such air channels were present, then air from Within the binmight pass through the tube and through the opening 155 into thepassageway 156 and disturb the air-fuel ratio to the furnace.

The fire in the'furnace once having been started and with a suitableamount of sawdust in the bin the system continues to supply fuel to thefurnace as required.

As the steam pressure in the boiler increases, the Sylphon bellows 63,will respond to the increase of pressure. As such pressure increases thebellows will be extended to thusmove the finger 59 to slow the Reevesdrive. The reversing motor actuates the swinging lever 47 in accordancewith its direction of rotation to change the driving ratio of the Reevesdrive to change the speed of rotation of the conveyor shaft 19. When thepressure in the boiler builds up to a predetermined value the reversingmotor will stop. As the pressure in the boiler drops, because of thediscontinuation of fuel supplied to its furnace, the Sylphon bellows 63will respond to such drop in temperature and will eventually againoperate the reversing motor 50 in a direction to cause rotation of theconveyor 18 to resume the supply of fuel to the furnace.

This continues intermittently as long as the furnace is in operation.

I claim as my invention:

In a fuel burning system for sawdust-like material, a fuel duct havingan open end arranged to receive fuel and having a closed end oppositesaid open end, a conveyor screw in said dust having a terminal endspaced from said closed end of said duct for compaction of thesawdust-like material between said closed end of said duct and saidterminal end of said conveyor screw, continuously variable drive meansfor rotating said conveyor screw, an air duct extending transversely ofand below said fuel duct adjacent said closed end and beyond saidterminal end of said screw, said fuel duct having a transverse openingaligned above said air duct and having a width less than one-half thewidth of said air duct for passage of the sawdust-like material intosaid air duct, and a blower having an outlet for communicating with afuel burner and having an inlet connected to one end of said air duct,the other end of said air duct being in "communication with theatmosphere.

References Cited in the file of this patent UNITED STATES PATENTS

